Sedimentology, geochemistry, economic potential and palaeogeography of an Upper Cretaceous phosphorite belt in the southeastern desert of Jordan

Abstract

Jordan is well known for its Cretaceous phosphorite deposits. These comprise the phosphorite-bearing sediments which overlie the main chert facies of the Amman Formation. Phosphorites have been mined since the 1950s in north and central Jordan. Tectonic ‘windows’ or ‘inliers’ reveal the Upper Cretaceous sequence in the SE desert of Jordan in several localities underlying the main chert facies. These newly discovered phosphorite deposits are sandy with P2O5ranging from less than 1% to more than 33%. They form a belt extending in a NE-SW direction for about 200km, and into NW Saudi Arabia. The equivalent sequence in western Jordan is fully calcareous and devoid of phosphorites. The southern segment of this belt (about 80km) may have as much as 4 billion tonnes of phosphorite containing more than 20% P2O5. These phosphorites are postulated to have been deposited in a restricted nearshore environment by local upwelling around the Sirhan Arch, a mid Cretaceous positive feature in the study area which also served as the source for sand.